WorksheetsQUIZ1-EM1
Total questions: 10
Worksheet time: 5mins
The energy stored in a magnetic field is given by ____________ where L=self-inductance and Rl=reluctance
1/2 Li2
1/2 (mmf*Rl)2
1/2∅Rl
1/2 φ2i
For a linear electromagnetic circuit, which of the following statement is true?
Field energy is less than the Co-energy
Field energy is equal to the Co-energy
Field energy is greater than the Co-energy
Co-energy is zero
Which of the following are examples of doubly-excited magnetic systems?
Synchronous Machines
Loudspeakers and Tachometers
D.C Shunt Machines
All of the mentioned
In a doubly excited magnetic system with salient pole type stator and rotor, if the rotor is not allowed to move, then the equation for magnetic field stored energy in establishing the currents from zero to is and ir is __________
Wfld=1/2 is2Ls+1/2 ir2Lr
Wfld=1/2 is2Ls+Mrs is ir
Wfld=1/2 is2Ls+1/2 ir2Lr+Mrs is ir
Wfld=1/2 ir2Lr+Mrs is ir
In a doubly excited magnetic system of salient pole type stator and rotor, the reluctance torque is present only when _____________
both stator and rotor currents are acting
stator current is acting alone
rotor current is acting alone
any of the stator or rotor currents acting alone
Which component of torque in the following equation is called the electromagnetic torque of electromagnetic energy conversion device?
Te=1/2is2dLs/dθr+1/2ir2dLr/dθr+isirdMsr/dθr
1/2is2dLs/dθr
1/2ir2dLr/dθr
isirdMsr/dθr
all of the mentioned
Which of the following statements are true about electromagnetic torques and reluctance torques?
(i) electromagnetic torque can exist only if both windings carry current (ii) reluctance torque depends on the direction of current in stator or rotor windings (iii) reluctance torque doesn't depend on the direction of current in stator or rotor windings (iv) electromagnetic torque depend on the direction of currents is and ir (v) electromagnetic torque doesn't depend on the direction of currents is and ir
(i), (ii), (iii)
(ii), (iii), (v)
(i), (iii), (iv)
(ii), (iii), (iv)
Direction of induced emf is determined by __________
Fleming’s left hand rule
Fleming’s right hand rule
Faraday’s law
Right hand thumb rule
“The direction of an induced e.m.f. is always such that it tends to set up a current opposing the motion or the change of flux responsible for inducing that e.m.f.”, this is the statement for?
Fleming’s left hand rule
Fleming’s right hand rule
Faraday’s law
Lenz’s law
The equivalent of the current I in magnetic ohm’s law is?
Flux
Reluctance
MMF
Resistance
